It found that Tauranga was among the world's most expensive housing markets, just ahead of Auckland, and behind Hong Kong, Vancouver, Sydney, Melbourne, Santa Cruz, San Jose, and Los Angeles, respectively.

It comes down to the median household income of people living in Tauranga. It currently sits at $68,000 per year and yet house prices are at a median $623,000.

Auckland isn't much better, where the median income is $94,400 per year and the median house price is $845,000.

The next least affordable places in New Zealand are Hamilton-Waikato, followed by Napier-Hastings, Wellington, Dunedin, Christchurch and Palmerston North-Manawatu.

New Zealand's housing unaffordability is "severe", the report says. It notes how Auckland is the seventh least affordable among the 91 major global housing markets, and has been severely unaffordable in all 15 previous reports.

In New Zealand, as in Australia, housing "had been affordable until approximately a quarter century ago", the report says, explaining how this led to a land scarcity and pushed up house prices.

"Public opinion placed the issue of housing affordability to the top of the policy agenda in the last three national elections," the study notes.

The Government's Urban Growth Agenda is highlighted, which calls for intensified residential development on both greenfield and infill sites. It also notes how the Auckland urban containment boundary is to be abolished.

National leader and Tauranga MP Simon Bridges said the report "nails" the problem. He believes development of the country's housing market has been restrained by the Resource Management Act (RMA).

"This is something that's a long-run problem. It says that effectively we've kept things in a regulatory straitjacket," he told The AM Show on Monday.

"Think about Tauranga, it's got plenty of land. Out Papamoa East, you could build something like 35,000-40,000 more houses."

Mr Bridges said successive governments have "dropped the ball on this".

The former National-led government passed RMA reforms in April 2017, but those reforms did not go as far as National wanted after it struggled to get support from other parties.

"Labour and the Greens didn't want to know... I promise you this year you will see from us in National wholesale reform. You'll see something bold," Mr Bridges said.

National MP Stuart Smith said the party will release its draft legislation this year to replace the RMA.

"We want to simplify this complex but vital Act to give people more certainty on issues that come under the RMA," he wrote in an opinion piece this month.

"By doing this, we want to make it easier to build houses, allow important projects to get off the ground and reduce environmental impacts."